For example, in the manufacturing processes of semiconductor devices, circuits are formed by pattern transfer to bare wafers and etching. In manufacturing processes of various semiconductor devices for circuit forming, foreign substances adhered to wafer surfaces, defects existing on wafer surfaces, and the like are major factors of reducing yields. The foreign substances adhered to wafer surfaces and the defects existing on wafer surfaces are controlled in each manufacturing process, where the foreign substances adhered to bare wafer surfaces, the defects existing on the wafer surface, and the like can be detected by a surface inspection apparatus with high sensitivity and high throughput.
The methods for inspecting wafer surfaces for foreign substances and defects can be roughly classified into the methods using a charged-particle beam such as an electron beam and the methods using light, and the methods using light include the methods of taking an image of the wafer surface by use of a camera and analyzing the image information and the methods of detecting with a light receiving element the light scattered by the wafer surface and analyzing the magnitude of the light scattering. The Patent Literature 1 discloses an example of the latter methods, and the Patent Literature 2 discloses a technique related to the present invention. That is, the Patent Literature 2 discloses a method enabling detection of small defects foreign substances or the like on inspection objects having great of surface conditions, by producing a margin in the dynamic range of an amplifier by DC (direct current) offset removal and increasing the gain.